The song features: several changes in tempo, a sped-up double-tracked vocal part by Barrett, while Mason simultaneously sings the normal part[5][6] (one of the rare moments he ever sang on a Floyd record),[7] a range of bells,[8] crowd noises,[8] an instrumental section that continually increases in speed featuring wah-wah guitar solos and keyboards, and surreal lyrics.[9] Barrett is only clearly audible on one line in the song, "she'll be scrubbing bubbles on all fours".[5]

The two tracks were arranged to be released as a single on 8 September, before it was vetoed by the band's record company, EMI.[10] The song was again scheduled for release, this time with "Vegetable Man" as the B-side, but cancelled and both tracks remain unreleased.[1][11]

A promotional video was made for the track, directed by poet Spike Hawkins.[1] A final studio cut of "Scream Thy Last Scream" was completed along with a somewhat different BBC radio version (which features both Barrett and Mason on lead vocals)[12] and even some live recordings.[13] All are widely available on bootleg recordings.[14] A late-Barrett era rendition was recorded live in Rotterdam in November 1967, at the Hippy-Happy Fair.[15] Producer Malcolm Jones (who produced Barrett's The Madcap Laughs solo album) had remixed "Vegetable Man" and "Scream Thy Last Scream",[16] for inclusion on the Barrett rarities album Opel (1988), however the band blocked its inclusion.[17][18]

The song's chord progression and melody were later reworked for Barrett's song "Baby Lemonade", from his 1970 album Barrett.